Case description: A 13-year-old boy with accelerated growth underwent MRI for pituitary assessment, which incidentally demonstrated a non-enhancing, T2 hyperintense right occipital lesion. No diffusion weighted imaging (DWI) sequences were obtained, and the lesion was suspected to represent encephalomalacia. Five years later, he developed left visual field difficulties and repeat MRI identified right occipital lesional growth with high DWI and low apparent diffusion coefficient (ADC) signal. The patient underwent resection of the right occipital lesion. Histopathology revealed keratin encapsulated by squamous epithelium, consistent with an epidermoid cyst. Our patient is currently doing well, and his left visual field vision is improved.

Discussion: Intracranial epidermoid cysts comprise 1% of primary intracranial tumors and are derived from ectodermal inclusions during neural tube closure. They usually present in middle age due to mass effect on adjacent structures. Epidermoid cysts most commonly occur at the cerebellopontine angle and parasellar region. A cortical location of an intracranial epidermoid cyst, as in our patient’s case, is very rare. The signal intensity of the epidermoid cyst on MRI is variable due to its composition of keratin and lipids and there is usually no associated edema. Total surgical excision is the mainstay of treatment for intracranial epidermoid cysts. Recurrence is not uncommon, but growth is usually slow over many years.